The fabrication of electronic assemblies, such as integrated circuit chips and fiber optic cables, requires alignment inspection of the device at various phases of the fabrication process. Such alignment inspection procedures utilize vision systems or image processing systems (systems that capture images, digitize them and use a computer to perform image analysis) to align devices and guide the fabrication machine for correct placement and/or alignment of components.
In conventional systems, post attach inspection is used to determine if changes in fabrication machine position are necessary to effect proper placement and/or alignment. As such, these conventional systems can only compensate for misalignment after such improper alignment is made, thereby negatively effecting yield and throughput. These conventional systems have additional drawbacks in that they are unable to easily compensate for variations in the system due to thermal changes, for example, requiring periodic checking of completed devices further impacting device yield and negatively impacting manufacturing time.
In conventional systems the vision system (shown in FIG. 11) consists of two image devices, a first image device 1104 placed below the optical plane 1112 and views objects upward and a second image device 1102 placed above the optical plane and views objects downward. These conventional systems have drawbacks, in that in addition to requiring more than one image device, they are unable to easily compensate for variations in the system due to thermal changes, for example.